MoneyPickup.cs

using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class MoneyPickup : MonoBehaviour
{
    public int cashValue = 1;

    private void OnTriggerEnter2D(Collider2D other) {
        if(other.tag == "Player") {
            IInventory inventory = other.GetComponent<IInventory>();

            if(inventory != null){
                inventory.Money = inventory.Money + cashValue;
                print("Player inventory has " + inventory.Money + " money in it.");
                gameObject.SetActive(false);
            }
        }
    }
}